linux-kernel - Re: [Patch V2 6/9] I2C: Add smbus word/block process call helper function

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Message-ID: <53776B32.8010400@intel.com>
Date:	Sat, 17 May 2014 21:59:14 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	rjw@...ysocki.net, mika.westerberg@...ux.intel.com,
	awilliam@...hat.com, lenb@...nel.org, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [Patch V2 6/9] I2C: Add smbus word/block process call helper
 function

On 05/17/2014 06:21 PM, Wolfram Sang wrote:
> On Mon, Apr 28, 2014 at 10:27:45PM +0800, Lan Tianyu wrote:
>> Add i2c_smbus_word/block_proc_call() helper function. These will be used
>> in the implementation of i2c ACPI address space handler.
>>
>> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
>> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
>> ---
>>   drivers/i2c/i2c-core.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/i2c.h    |  4 ++++
>>   2 files changed, 60 insertions(+)
>>
>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>> index 3bf0048..638befd 100644
>> --- a/drivers/i2c/i2c-core.c
>> +++ b/drivers/i2c/i2c-core.c
>> @@ -2306,6 +2306,30 @@ s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
>>   EXPORT_SYMBOL(i2c_smbus_write_word_data);
>>
>>   /**
>> + * i2c_smbus_word_proc_call - SMBus "word proc call" protocol
>> + * @client: Handle to slave device
>> + * @command: Byte interpreted by slave
>> + * @value: 16-bit "word" being written
>> + *
>> + * This executes the SMBus "word proc all" protocol, returning negative errno
>> + * else a 16-bit unsigned "word" received from the device.
>> + */
>> +s32 i2c_smbus_word_proc_call(const struct i2c_client *client, u8 command,
>> +			      u16 value)
>> +{
>> +	union i2c_smbus_data data;
>> +	int status;
>> +
>> +	data.word = value;
>> +	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
>> +			      I2C_SMBUS_READ, command,
>> +			      I2C_SMBUS_PROC_CALL, &data);
>> +
>> +	return (status < 0) ? status : data.word;
>> +}
>> +EXPORT_SYMBOL(i2c_smbus_word_proc_call);
>> +
>> +/**
>
> Same as smbus_quick function before, documentation updates are missing.
> Also similar, we had such a function before which was removed due to no
> users? It looks very much like the function here, so we should stick to
> the old naming IMO. Is it the old one? Such information would be nice
> since it affects reviewing.

Yes, there was an old function and commit c8110933 removed it. Sorry, I didn't 
that before. I will bring the old one back.

>
>>    * i2c_smbus_read_block_data - SMBus "block read" protocol
>>    * @client: Handle to slave device
>>    * @command: Byte interpreted by slave
>> @@ -2362,6 +2386,38 @@ s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
>>   }
>>   EXPORT_SYMBOL(i2c_smbus_write_block_data);
>>
>> +/**
>> + * i2c_smbus_block_proc_call - SMBus "block write" protocol
>> + * @client: Handle to slave device
>> + * @command: Byte interpreted by slave
>> + * @length: Size of data block; SMBus allows at most 32 bytes
>> + * @values: Byte array which will be written.
>> + *
>> + * This executes the SMBus "block proc call" protocol, returning negative errno
>> + * else the number of read bytes.
>> + */
>> +s32 i2c_smbus_block_proc_call(const struct i2c_client *client, u8 command,
>> +			       u8 length, u8 *values)
>
> Please rename to "i2c_smbus_block_process_call" as the old function was
> named. Needs documentation updates.
>
>> +	if (length > I2C_SMBUS_BLOCK_MAX)
>> +		length = I2C_SMBUS_BLOCK_MAX;
>
> I think we should return an error here.

Ok.

>
> BTW what were your test scenarios for these functions and smbus quick?
>

 From ACPI spec, Read/Write quick and Word/Block process call protocol will be 
used by Bios ACPI code. But so far, I don't find such machines. So these 
functions has not been tested.




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